338 PHILOSOPHY OF ZOOLOGY. 



The mouth in many fishes is terminal, while, in others, 

 it has a ventral aspect, being placed beneath a projecting 

 snout. The opening in all cases is transverse. The bones 

 of the upper jaw are chiefly the maxillary and intermax- 

 illary. The latter frequently occupy a large portion of the 

 gape, while the former extend beyond the gape like a move- 

 able process. These bones are loosely connected with the 

 cranium by means of palatine and cheek bones, which form 

 a sort of inner jaw, to which the lower jaw is articulated. 

 The articulations admit, in many cases, of extensive mo- 

 tion, and enable the animal to form with them a sort of tu- 

 bular proboscis. 



The tongue is supported by a largely divided os hyoides, 

 which gives support to the arches of the gills, the bones of 

 the gill-lidj and those of the gill-flap. 



The teeth are situate, according to the species, not only 

 on the lower jaw, the maxillary and intermaxillary, but on 

 the vomer, the palate, the gill-arches, the tongue, and the 

 walls of the pharynx. In some species, the teeth are form- 

 ed in sockets, as among the Mammifera ; in others, they 

 seem to be continuations of the bones, while in a few they 

 may be viewed as epiphyses. The last kind appear to be 

 readily reproduced *. In nearly all fishes the teeth are 

 bent inwards, and thus serve to retain the food. The 

 pharynx appears to be a direct continuation of the mouth. 



The gidlet, on account of the absence of a neck, is re- 

 markably short in fishes. In some, indeed, the stomach 

 seems to open directly into the mouth. Where the gullet 

 is obvious, it exhibits few peculiarities of structure. In 

 some of the branchiostegi it is beset with tufts of hair re- 

 sembling a fine net-work. It is in general capable of great 



'Phil. Trans. 1T81, p, 279. 



